Burning forest to make land suitable for farming or to rear livestock is a widespread practice in many parts of the developing world. Nearly three billion people around the world are exposed to contaminants from biomass burning as a result of farming practices, deforestation, and burning wood or charcoal for fuel.
A team of Brazilian researchers studied particles released during the burning of biomass using material they collected in the Amazon forest, to assess how inhaling them can impact on human health.
To do this, they exposed human lung tissue to particulate matter smaller than 10 microns (10 μm), which is commonly emitted as a result of these fires and can reach the lung alveoli.
“I hope our findings will serve as an incentive so particulate matter smaller than 10 μm is better studied, and its environmental concentrations regulated in regions strongly impacted by biomass burning.”
Nilmara de Oliveira Alves Brito
A high amount of pro-inflammatory molecules were produced by the cells almost as soon as exposure began. The cells also started to release significance amounts of Reactive Oxygen Species (ROS), a type of substance that damages cellular structures when produced in high quantities.
The cells then stopped multiplying, and this “suggests damage in the DNA”, says Nilmara de Oliveira Alves Brito, lead author of the article, published in the journal Scientific Reports, and a postodoctoral fellow at Brazil’s research foundation FAPESP.
The first signs of damage were observed just 24 hours after of exposure. “As time passed, the genetic damage increased, and cells underwent apoptosis [non-inflammatory cell death] and necrosis [cell death that leads to inflammation]”, said Alves Brito.
Three days later, 33 per cent of the exposed cells had died by necrosis, compared with 2 per cent of cells without exposure. According to Brito, the surviving cells also showed signs of DNA damage “which means they can be predisposed to developing cancer in the future”.
During their analysis of compounds released from the substances picked up in the Amazon, the researchers became aware of the presence of a range of polycyclic aromatic hydrocarbons (HAPs), which are typically released as a result of burning organic materials, including cooked steak. Many HAPs are already recognised as carcinogenic, however most of them have yet to be studied.
On analysing the HAPs identified, the researchers discovered that a particular compound, retene (methyl isopropyl phenanthrene) was present in larger quantities than particles smaller than 10 μm.
On repeating the experiment using only this compound, at the concentrations found in the field, they found that retene can by itself provoke DNA damage and cellular death.
“We did not find information about retene’s toxicity in scientific literature,” says Alves Brito. “I hope our findings will serve as an incentive so particulate matter smaller than 10 μm is better studied, and its environmental concentrations regulated in regions strongly impacted by biomass burning.” An issue of concern is the capacity of this type of pollutant to travel long distances. Retene can be found in the outdoor air of big cities like Sao Paulo, according to Paulo Artaxo, from the Institute of Physics at the University of Sao Paulo, and co-author of the research.
Its presence is likely a consequence of burning sugarcane and other kinds of biomass around the city, which is the second largest in Brazil, he added.
Taken from the FAPESP Agency, a SciDev.Net donor, and edited by SciDev.Net’s Latin America and the Caribbean desk.
This piece was originally published by SciDev.Net’s Latin America and Caribbean desk.